A kind of single-mode optical fiber and its preparation method

Abstract

A single-mode optical fiber and its preparation method. The bare optical fiber includes a core layer and a cladding layer. The core layer includes a first core layer, a second core layer, and an inner cladding layer. The relative refractive index difference of the first core layer is 0.2%≤Δ 1 ≤0.35%, the relative refractive index difference of the second core layer is 0.15%≤Δ 2 ≤0.25%, the refractive index radius of the inner cladding is 24μm~36μm, and the relative refractive index difference of the inner cladding is -0.12%≤Δ 3 ≤0%. The cladding, including the depressed cladding and the outer cladding, the relative refractive index difference of the depressed cladding is -0.40%≤Δ 4 ≤‑0.28%, the outer cladding is high hardness pure quartz casing. The two-stage sleeve and core rod are assembled and drawn on-line, and the optical fiber is annealed multiple times during the drawing process, and the surface of the optical fiber is coated with a low-modulus coating and a high-modulus coating on the outside to prepare a low-loss, large effective area, and high-strength optical fiber. The method is simple, the viscosity of the core rod can be adjusted according to the requirement, and there is no need to use a pure silicon core solution to reduce the attenuation of the optical fiber, which is conducive to large-scale production.

Description

technical field [0001] The invention relates to a single-mode optical fiber and a preparation method thereof. Background technique [0002] As we all know, with the rapid development of optical fiber communication technology, the existing conventional G.652 optical fiber can no longer meet the requirements of high-speed optical communication backbone transmission such as 400G or even 1T. . As the main indicators and symptoms of optical fiber signal transmission, reducing fiber loss and increasing the effective area are generally considered by the industry to be the key factors to improve optical fiber transmission capacity and increase transmission distance. [0003] At present, when the industry is used to prepare low-loss, large-effective-area optical fibers, most of them use VAD and PCVD methods to make core rods, but the refractive index of optical fibers made by VAD is difficult to control, and PCVD cannot improve the single fiber due to the influence of the size of th...

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Problems solved by technology

[0004] Chinese patent ZL201310409732 discloses a method for preparing a low-loss optical fiber using a pure silicon core scheme. However, due to the pure silicon core design, it is extremely difficult to match the viscosity of the core layer and the cladding layer, and the uniformity of the radial refractive index is poor. Prepared by PCVD in-tube method, the process is complicated and the requirements for fiber drawing are extremely high, which is not conducive to mass production

201510355895.5 discloses a method for preparing a low-loss, large effective area, and high-strength single-mode optical fiber under a germanium-fluorine co-doped core. Although the core rod is prepared by the VAD method, the design of the refractive index profile is very complicated and the steps are cumbersome, which is not conducive to large-scale production. Production

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